Buy a BIG pile of magazines of every conceivable sort, and clip every
coupon for a catalog, trial product, free brochure, etc. Specialty
magazines have the most, such as hobbies or sports (or computers).
Your victim should be deluged with junk mail (and since most such
lists get sold to other lists, the response will be a geometric
function of the number of clips you send).
A friend of mine and I once almost started a junkmail war, but formed
a truce before, because we knew it would follow us around for years...